Or it might be that it's actually a good mechanic that speeds up play a lot and take some unnecessary hassle out of skills resolution. That's my take on it, even though 4e and 5e did not follow suit (I'm sure about 5e and pretty sure about 4e). But 5e has even better, automatic success or failure.
It's the "automatic" part that bothers me, as so many things aren't automatic at all.
Why ? Just for the pleasure of rolling the dice ? Of frustrating the players ?
Realism, mostly. Using the "search the room" example, if I hide somethine really well in a room - say, in a very-hard-to-detect secret compartment in the floor - and I send 100 different people (or groups) in to search for it, even if they have all day the odds of all 100 groups coming out having found it are negligible. Ideally, if my hiding job is good enough none of them find it; but it's inevitable some will just by fluke and some others will by either skill or deduction or whatever.
This is what I want the game to reflect: that even when there's no pressure you can still blow it; and that even if something's normally beyond one's capability to find sometimes you'll find it anyway by sheer luck. Hence, a roll (ONE roll, no rerolls) determines the best you'll do in this situation, instead of Take-20.
It's not a roll-playing game.
On this I agree. That said, Take-20 is still a "roll" in my view even though a die isn't actually rolled, just like an intentional walk in baseball is still a walk except without the four pitches being thrown.
Or it serves to make exploration story-driven rather than more random. Again, YCMV and to each his own, I can understand both ways of wanting to play the game.
I'm not after story-driven, though, in that sense; nor am I all that concerned about speeding up play by skipping over details (some here seem to want to sacrifice half the game on the altar of speed). I'd rather see the story emerge from the detailed run of play.
It works for a lot of us, you know, it's about role-playing, the character might have thought about bringing something that the player did not know about. I don't have to be a wizard to play one, which is a good thing. And I have better things to do than to list extra pairs of socks on my character sheet, for example.
Problem is, this allows players to meta-game their characters into always just happening to have exactly what they need when they need it; which means that anyone who bothers to put the forethought into equipping their character properly ahead of time is wasting their time, and also means some challenges might be easier to overcome than they should be - or even outright negated.
Never mind that even mundane gear costs money, and particularly at low levels not every character can afford a complete kit.
Yes it's about role-playing - we agree there! But sometimes that role-playing is going to include "Damn, I forgot to bring that." or "Damn, I wanted to pick one of those up last time in town but couldn't afford it!"